The whaling history of New London probably had its beginnings not long after the town's establishment at a natural harbor on the Thames River in 1645. This was drift and inshore whaling, patterned after Indian practices. The first whaling ship sailed from New London in 1718, when the sloop Society made a cruise along the Carolinas. The system of trying the oil on board ship, which made possible long voyages, was inaugurated in 1761; but New London developed more slowly than other whaling ports, and it was not until 1804 that the first successful whaling company was organized. The industry's high point was reached in 1845, when 14 firms operated 81 vessels totaling 27,273 tons. In 1847 New London passed Nantucket to become the nation's second whaling port, bowing only to New Bedford.

The search for sperm oil and whalebone led New Londoners to the South Atlantic, the Antarctic, the South Pacific, Indian Ocean, the North Pacific and finally to Spitzbergen Ocean, Hudson Bay and nearby waters. More than 60 whaling agents directed the operations of the whaling industry until 1909. An agent procured capital, signed on master and crew, arranged for insurance and after the voyage distributed the profits to investors and "lays," or fractions of the earnings, to master and crew. The agent usually held the controlling interest in a voyage and frequently operated a supplying business.

It was the master of the ship, however, who determined the success or failure of a voyage. Regardless of the captains' capabilities, many owners kept a close rein over them as to expenses and the take of oil and bone. In their turn, captains were absolute monarchs at sea. The crews originally were made up of men living in the New London area. Over the years, as pay and working conditions worsened, agents resorted to "land sharks" who enticed and shanghaied residents from inland cities and natives off islands. Living conditions of most crews were crowded and dirty, and mutiny became a common danger. Desertions in foreign ports were a problem. Many sailors lost their lives in the capture of whales; falling from aloft ranked second as a cause of death.

Starting in 1849, several events brought about the decline of the New London whaling industry. The California gold rush lured away at least 25 captains and uncounted seamen from New London. The financial panic of 1857 was followed by the Civil War, with shortages of capital, men and ships as well as the seizures of vessels by Confederate raiders. In 1859 the first Pennsylvania oil refinery began operations, and kerosene became cheaper than whale oil. This chain of reverses was climaxed by the Arctic disaster of 1871, when thirty-nine U. S. captains ignored the Eskimoes' warnings of an early freeze and the vessels were trapped by ice.

The last New London-owned whaling ship, the fittingly-named Era, sailed on a five-month voyage in 1892. Two other ships, both owned elsewhere, sailed from the port, finally the Margaret in 1909.